Vault 87 muties actually have a different skeleton from Mariposa muties. (Mariposa ones are all hunched over, 87ers stand tall) You sure that would work?
lol, apparently not. The meshes are
just different enough that the textures don't fit quite perfectly.
HOWEVER! The Fallout 3 super mutant models and textures both exist in the New Vegas .bsa files, and there's a whole bunch of New Vegas-style mutant texture replacers on Fallout3Nexus. http://www.fallout3nexus.com/downloads/file.php?id=15157, for example, is close enough to look pretty good alongside the NV muties.